A prefabricated fireplace comprises a firebox and flue enclosed by concrete cast as a unit. The firebox has inner walls defining a fuel box in which combustion occurs and outer walls which define a circulation space around the fuel box for room air to be heated. The fuel box is sealed from the room by glass doors which open to supply fuel and, when closed, allow light and heat to pass, and oxygen reaches the fire through an outdoor duct. The prefabricated fireplace has around its base edges a plurality of weldplates which allow quick installation by welding to metal base plates cast in the foundation. The prefabricated fireplace may also include means to interface with home forced-air and water heating systems for heating of air and water.